Sirion 2 reversing sensors not working


Hi, recently my reversing sensors on my 2006 SE suddenly stopped working. I want to see if I can solve the problem myself before taking it to a reputable local auto-electrical specialist. Is there anything obvious I should be checking for? I thought it might be a fuse at first but the reversing lights are ok and I'm assuming the sensors are wired into the same circuit? I'm probably imagining this as it doesn't seem to make sense, but it really feels like its easier to engage reverse gear now than it ever has done.

Thanks in advance if someone can help me.